Eunice here from the social care team at Shopify. Thanks for posting!
This is actually a really simple fix, and I'm happy to inform you that there is no coding required. You can customize your online store by changing the default text in your theme. For example, you can change "Cart" to "Shopping bag", or "Sold out" to "Unavailable". Each theme includes a language editor where you can edit the text for your theme.
To change the word 'Company' to 'Store' on the checkout page just follow these steps:
1) From your Shopify admin, go to Online Store > Themes.
2) Find the theme that you want to edit, and then click Actions > Edit languages.
3) Click the tab that includes the text that you want to change, or search for it using the 'search translations' tool at the top of the page.
4) Edit the text.
5) Click Save.
To find out more about the language editor, and what it does, just head on over to our help desk.